The present invention relates to a sealed connection device for ventilation filters used in particular in the nuclear industry.
It relates more precisely to a device used more particularly in a hostile environment, on a ventilation circuit.
Many filters, with filter medium, are used in the nuclear industry for filtering contaminated gas, e.g. on the internal ventilation circuits of confinement chambers. Very High Efficiency (VHE) and High Efficiency (HE) filters are known in particular.
Such filters must be mounted in sealed manner. All of the contaminated gas must pass therethrough.
They are generally tightly disposed inside a housing, with the help of a sealing system: e.g. gaskets.
In the prior art, filters are mounted in said housing on a plate, for example, and they are pressed against the flange of the ventilation circuit.
They are pressed by means of springs which exert a large amount of pressure on said plate, thereby ensuring sealing.
However, that pressure does not suffice to hold the filter in place in the event of an earthquake.
That known filter connecting device has major drawbacks.
In order to achieve the sealed connection, the force with which the filter is pressed against the flange must firstly be large.
Unfortunately, the force is generally exerted by means of pliers or remote manipulators.
Secondly, during the operation of replacing filtersxe2x80x94said operation itself also generally being performed by remote manipulationxe2x80x94the filter must be forced into the housing between the flange of the circuit and the plate.
This implies deterioration due to rubbing against its sealing system: e.g. gaskets at its periphery.
The invention proposes a new sealed connection device which mitigates those drawbacks. Said device can be considered as an improvement to the present system described above, making use of a plate under tension, by means of springs.
The device of the invention includes:
a cylindrical housing designed to receive said filter, the housing being fixed at a second end to a ventilation circuit flange and having a first end mounted on a companion flange, the companion flange being held in resilient manner under axial tension by holding means under tension;
a sheath coaxial with and secured to said housing, about which sheath said companion flange slides axially in sealed manner, on which sheath there are disposed said holding means under tension, and to which sheath there are secured three fixed wheels projecting outwards therefrom;
a cam surrounding said sheath over a certain length and constituted by a ring having three ramps each in the form of a helical segment, said ramps receiving respective ones of the wheels, turning of said cam causing said companion flange to move in axial translation; and
means for turning said cam.
Turning said ramped cam, enclosing the three wheels connected to the fixed sheath, causes said cam to slide towards the first end of the housing, and after taking up a certain amount of slack, towards the first end of the companion flange.
The retraction of the companion flange which followsxe2x80x94by said companion flange sliding towards the first end of the housing, or in fact by compressing the holding means under tensionxe2x80x94enables a new filter to be put into place, without the sealed joints being rubbed in a damaging manner.
Once the new filter has been put into place, turning the cam in the other directionxe2x80x94which causes it to slide towards the second end of the housingxe2x80x94xe2x80x9cfreesxe2x80x9d the companion flange which presses said filter against the flange. The means for keeping the companion flange under axial tension exert sufficient pressure.
Said means can consist of prestressed springs and advantageously of prestressed spring washers disposed against a first end of the companion flange.
By means of the mechanical advantage provided by the cam, the device of the invention enables the small capability of the pliers or remote manipulators used to be reconciled with the significant pressing force required to press the filter against the flange of the ventilation circuit. The pressing force which is higher than in the prior art improves both the sealing of the circuit and the ability of the filter to withstand an earthquake.
Naturally and in like manner, the device of the invention can easily be manipulated by hand, via a glove box.
Such a device can thus easily be manipulated remotely; its use makes it possible to ensure both that the circuit is sealed and that the filter can withstand an earthquake. Finally, such a device is very compact.
It should be noted that the sheath of the device of the invention advantageously includes, at its first end, a cylindrical rim which makes it possible to extend the ventilation circuit by means of a connecting flange.